LTE Signaling
R&S
®
CMW-KM5xx/-KS5xx
23
User Manual 1173.9628.02 ─ 16
After a reconfiguration of the baseband input settings of the R&S AMU200A, turn
the downlink signal at the signaling application off and on again.
2.2.5 Internal Fading
Testing under realistic air interface conditions is important in order to verify the receiver
performance and the correct operation of the protocol stack implementation. For exam-
ple, block error rates, throughput performance and correct operation of layer 1 proce-
dures like Hybrid Automatic Repeat Request (HARQ) retransmission can be evaluated.
The internal fading module comes with a fading simulator and AWGN generator that
can be selectively enabled. It manipulates the generated downlink I/Q data stream to
emulate typical signal conditions at the receiver.
The following options are required to use the internal fading simulator in LTE:
●
fader I/Q board R&S CMW-B510F and/or R&S CMW-B520F (depends on scenario)
●
option R&S CMW-KS510 "LTE R8, SISO, advanced signaling" for scenarios with-
out carrier aggregation
●
option R&S CMW-KS512 "LTE R10, CA, advanced signaling" for scenarios with
carrier aggregation
●
option R&S CMW-KE100 "Basic Fading support: AWGN generator"
●
option R&S CMW-KE500 "LTE Fading Profiles TS 36.521, excerpts"
●
option R&S CMW-KE501 "LTE Fading Profiles MIMO 4x2 from TS 36.521 B2.3" for
MIMO 4x2
2.2.5.1
Fading Simulator
Multi-path fading is an effect which occurs in real world situations. A signal sent from
the base station follows the direct line of sight and/or takes routes with reflections. At
the receiving antenna this leads to a sum of phase shifted and, if the receiver is mov-
ing, frequency shifted signals.
The internal fading simulator supports multipath propagation conditions defined in
Annex B.2 of 3GPP TS 36.101.
A faded signal has a higher crest factor than an unfaded one. In order to avoid distor-
tion, the baseband signal must be attenuated before entering the fading module. The
necessary attenuation (insertion loss) depends on the selected fading profile.
In LTE signaling, the insertion loss at the baseband level can be calculated automati-
cally or set manually. It is automatically compensated on the HF level. This implies a
shift of the allowed DL power range to the same extent, but in opposite direction.
2.2.5.2
AWGN Generator
Additional White Gaussian Noise (AWGN) is typically modeled in receiver tests,
because it can lead to a decrease of throughput. The quality of the received signal is
affected by the ratio of the signal power to the surrounding traffic noise level (signal to
General Description
深圳德标仪器
135-1095-0799
